Tetracyclus emarginatus has slightly undulate and concave margins, while T. glans has rounded, convex margins. Tetracyclus rupestris valves are elliptic to circular, with a broad axial area.

LM scalebar = 10 µm
Iwb 0030 1  Tetracyclus Glans 001 Girdle Band Cropped Small Iwb 0026 1  Tglans 009 Cropped Adjusted Small Iwb 0026 1  Tglans 004 Cropped Adjusted Small Iwb 0026 1  Tglans 005 Cropped Adjusted Small Cas 183038 07282014 051 Adj Cropped Small Cas 183038 07282014 028 Test
Length Range
19.4-37.5 µm
Width Range
13-21 µm
Striae in 10 µm

Tetracyclus hinziae

Bishop and Spaulding 2015

Tetracyclus hinziae LM3 Tetracyclus hinziae LM1 Tetracyclus hinziae LM6 Tetracyclus hinziae LM7 Tetracyclus hinziae LM2 Tetracyclus hinziae LM4 Tetracyclus hinziae LM5
Length Range
8.2-35.5 µm
Width Range
5.6-14.0 µm
Striae in 10 µm

Tetracyclus rupestris

(Braun ex Rabenh.) Grunow in Van Heurck 1885

Tetracyclus rupestris LM4 Tetracyclus rupestris LM1 Tetracyclus rupestris LM6 Tetracyclus rupestris LM2 Tetracyclus rupestris LM7 Tetracyclus rupestris LM3 Tetracyclus rupestris LM5
Length Range
8.0-22.4 µm
Width Range
4.7-8.4 µm
Striae in 10 µm

Also compare to

Tetracyclus emarginatus

(Ehrenb.) W.Sm.